Effect of annealing treatment on the mechanical properties of spiked-shell aerographite particles

Abstract

The spiked-shell microparticles of aerographite exhibit excellent flexibility owing to their unique shell structures consisting of radially aligned hollow carbon nanorods. However, their flexibility is likely transitory, and fatigue damages related to imperfections in the crystallinity of their graphitic layers are observed upon cyclic deformation. In this study, aerographite microparticles were heat treated to examine the effects of annealing on their crystallinity and mechanical behaviors. Experimental results showed that the crystallinity of the particles was improved by annealing above 1600 °C; however, excess annealing at 2000 °C caused severe changes in the shell morphology, leading to a lack of flexibility. Single-particle-level compressive test results showed that the particles annealed at 1600 °C performed significantly better in terms of mechanical behaviors by reducing the probability of fracture due to large crack propagation. These particles also exhibited excellent flexibilities in their stress–strain relationships even after 100-times cycle tests. These findings suggest that annealing treatment at 1600 °C is an effective option to improve the mechanical properties of aerographite particles.